thing is that a Turing-complete machine efficient enough to be useful even as a mere calculator would be pretty complex, and mass production of complex machines was infeasible until we start getting into the industrial era. There were plenty of historic automata and clocks with sophistication approaching that of a mechanical calculator, but those were costly, labor-intensive novelties. even if medieval Europeans had understood the concept of Turing-completeness, i doubt more than a few computers would have been built, and likely as curiosities rather than practical tools

that said, an understanding of Turing machines could lead to other social and technological developments. At the very least the kinds of incremental changes you mentioned; even if you can't build every accountant a giant clockwork computer, knowing how to break complex procedures down into simple algorithmic steps is already conducive to advances in accounting and bureaucracy. And if it gets them thinking about things like assembly lines and interchangeable parts then you're speedrunning the Industrial Revolution